The invention relates to a pulley block having a covering element and to a method for mounting a covering element on a corresponding pulley block.
European patent EP1 457 455 B1 discloses such a pulley block in the form of a lower block for hoists. The lower block consists substantially of a central connecting element which intrinsically combines the function of an axle for cable pulleys rotatably mounted thereon at both ends and the function of a receiving element for a load hook. The load hook is mounted from below in the connecting element so as to be able to rotate about a vertical axis. The two cable pulleys are mounted coaxially with respect to one another and rotatably on opposite sides of the connecting element. Reeved load cables which run to the hoist are passed over the cable pulleys. The cable pulleys are provided with a covering hoods as accident protection means. The covering hoods are intended to prevent an operator's fingers or hands from being pulled in and jammed between the cable and cable pulley. Corresponding to the outer contour of the cable pulleys, the covering hoods have approximately a circular disk-shaped outer shape and are divided for mounting in the axial direction of the cable pulleys. The longitudinal division extends such that a cover-shaped outer hood part is produced which is placed in position laterally from the outside over the cable pulley until it comes to lie against an inner hood part where it is fastened. The circumferential separating line of the two hood parts extends, as seen in the radial direction of the cable pulleys, approximately in the region of the centre of the cable groove of the cable pulley. The inner hood part is annular and is formed with an outer circumferential edge, against which the outer hood part comes to lie, and is an integral component of the connecting element. Each of the covering hoods is provided with two inlet and outlet openings to ensure that the load cable passed around the cable pulley can enter and then exit the covering hood.
The cable openings have a width which corresponds approximately to the width of the cable groove of the cable pulley and therefore approximately to 3 times the load cable diameter. The length of the cable opening amounts to approximately 90° in relation to the circumference of the cable pulley or covering hood, wherein a separating web remains in the upper region of the covering hood between the two inlet and outlet openings. Assuming that the zero point of the angle specifications is positioned at the top in the centre of the covering hood, the first inlet and outlet opening begins approximately at 15° and runs to 105° and the second inlet and outlet opening extends from 255° to 345°. The inlet and outlet openings have such a large longitudinal extension in the circumferential direction of the cable pulley because the opening angle between the two strands of the load cables can vary between approximately 0° and 30° in dependence upon the configuration of the hoist and the spaced interval between the hoist and the lower block. In a corresponding manner, the run-out point of the load cable moves from the cable pulley in the region of the inlet and outlet openings and in the circumferential direction of the cable pulley. Since the diameter of the cable amounts to only a fraction of the length of the inlet and outlet opening, each of the inlet and outlet openings has a covering element inserted therein which closes the inlet and outlet opening with the exception of an opening for the cable. This opening is only slightly larger than the diameter of the cable. This prevents the possibility of the lower block operator's hand or fingers being pulled by the load cable into the remaining free space of the inlet and outlet opening. This covering element is held in the slot-shaped inlet and outlet opening so as to be displaceable in the circumferential direction of the cable pulley in order to move conjointly in parallel with the displacement of the cable run-out points in the inlet and outlet opening. In this case, on the one hand, the covering element covers the inlet and outlet opening from outside and, on the other hand, engages in a central region of the inlet and outlet opening—as seen in the circumferential direction of the cable pulley and in a central position of the covering element in relation to the inlet and outlet opening—around the edges of the cable opening in a u-shaped manner inwards. The covering element consists substantially of an upper main strip, a narrow web strip and a lower retaining strip which have an H-shaped cross-section with respect to one another. Moreover, the covering element is formed in one piece as a synthetic material injection-moulded part. For the purpose of mounting the covering element, said covering element is to be slid on at one end of the cable and the outer hood part is at least to be loosened in order to widen the slot-shaped inlet and outlet opening for insertion of the lower retaining strip.
DE 10 2008 059 071 B3 discloses a pulley block having a dividable covering element. The covering element is inserted into an inlet and outlet opening of a covering hood of the pulley block below the inlet and outlet opening such that in this case the inserted covering element does not engage through or behind the covering hood from above.
Further pulley blocks are disclosed in DE 10 2008 059 074 B3, DE 196 02 931 A1, U.S. Pat. No. 6,386,516 B1, U.S. Pat. No. 2,650,403 A and U.S. Pat. No. 2,728,552 A.